Fractal Properties of Heart Rate Dynamics: A New Biomarker for Anesthesia-Biphasic Changes in General Anesthesia and Decrease in Spinal Anesthesia.

Processed electroencephalogram (EEG) has been considered a useful tool for measuring the depth of anesthesia (DOA). However, because of its inability to detect the activities of the brain stem and spinal cord responsible for most of the vital signs, a new biomarker for measuring the multidimensional activities of the central nervous system under anesthesia is required. Detrended fluctuation analysis (DFA) is a new technique for detecting the scaling properties of nonstationary heart rate (HR) behavior. This study investigated the changes in fractal properties of heart rate variability (HRV), a nonlinear analysis, under intravenous propofol, inhalational desflurane, and spinal anesthesia. We compared the DFA method with traditional spectral analysis to evaluate its potential as an alternative biomarker under different levels of anesthesia. Eighty patients receiving elective procedures were randomly allocated different anesthesia. HRV was measured with spectral analysis and DFA short-term (4-11 beats) scaling exponent (DFAα1). An increase in DFAα1 followed by a decrease at higher concentrations during propofol or desflurane anesthesia is observed. Spinal anesthesia decreased the DFAα1 and low-/high-frequency ratio (LF/HF ratio). DFAα1 of HRV is a sensitive and specific method for distinguishing changes from baseline to anesthesia state. The DFAα1 provides a potential real-time biomarker to measure HRV as one of the multiple dimensions of the DOA.

Sample entropy analysis of EEG signals via artificial neural networks to model patients' consciousness level based on anesthesiologists experience.

Electroencephalogram (EEG) signals, as it can express the human brain's activities and reflect awareness, have been widely used in many research and medical equipment to build a noninvasive monitoring index to the depth of anesthesia (DOA). Bispectral (BIS) index monitor is one of the famous and important indicators for anesthesiologists primarily using EEG signals when assessing the DOA. In this study, an attempt is made to build a new indicator using EEG signals to provide a more valuable reference to the DOA for clinical researchers. The EEG signals are collected from patients under anesthetic surgery which are filtered using multivariate empirical mode decomposition (MEMD) method and analyzed using sample entropy (SampEn) analysis. The calculated signals from SampEn are utilized to train an artificial neural network (ANN) model through using expert assessment of consciousness level (EACL) which is assessed by experienced anesthesiologists as the target to train, validate, and test the ANN. The results that are achieved using the proposed system are compared to BIS index. The proposed system results show that it is not only having similar characteristic to BIS index but also more close to experienced anesthesiologists which illustrates the consciousness level and reflects the DOA successfully.

Impact of anesthetic methods on neonatal outcome in women receiving temporary balloon occlusion of the common iliac artery during cesarean section for placenta accreta.

OBJECTIVE: Placenta accreta is associated with significant maternal morbidity and is the leading indication for peripartum hysterectomy. In our institution, occlusion balloon catheters are commonly placed in bilateral common iliac arteries in order to reduce blood loss and facilitate surgery in patients with this obstetric complication. Few studies, however, have evaluated the effect of different anesthetic methods for cesarean hysterectomy on neonatal outcome. In this study, we compared Apgar scores among neonates born to mothers under general anesthesia with those who received regional anesthesia. CASE REPORTS: A retrospective analysis of 19 women with placenta accreta/percreta who underwent cesarean hysterectomy in our hospital, revealed that the 1-minute Apgar score was <7 in 4/12 neonates born to women who underwent general anesthesia and in 1/7 neonates born to mothers who received regional anesthesia. The 5-minute Apgar score was >7 after immediate resuscitation in all neonates. There were no significant differences in demographic data, induction-to-delivery period, or Apgar scores between the general and the regional anesthesia groups. CONCLUSION: We acknowledge that the retrospective nature of this study makes it difficult to conclude whether the different anesthesia management strategies had an impact on Apgar score; however, according to our clinical observation, regional anesthesia may be a better alternative in the induction-to-delivery period, especially for women with accreta/percreta and in situations in which poor neonatal outcome is expected.

Cervicofacial subcutaneous emphysema following tonsillectomy: implications for anesthesiologists.

Cervicofacial subcutaneous emphysema is an unusual complication following tonsillectomy. We present a 37-year-old male patient who, after receiving tonsillectomy, developed cervicofacial subcutaneous emphysema immediately following endotracheal extubation. Valsalva maneuvers evidenced by coughing and straining of the patient, and positive pressure ventilation by mask to alleviate laryngospasm in an emergency were believed to induce and exacerbate the emphysema. Fortunately, the patient was re-intubated and protected from further complication of pneumomediastinum or pneumothorax. The emphysema resolved 7 days later with conservative treatment, including broad-spectrum antibiotics and abstention from enteral intake. This case serves as a reminder that an unusual and unexpected complication can occur in a routine procedure. Methods to prevent this complication are discussed.

Anesthesia for cesarean section in a parturient with acute pulmonary edema--a case report.

Pulmonary edema is a rare complication in preeclampsia patients without pre-existing cardiac disease, tocolytic therapy, infection, or multiple gestations. We present a preeclamptic patient complicated by overwhelming pulmonary edema just prior to cesarean section and the massive edematous fluid production made it an exceptional challenge to the anesthesiologist on airway management. Emergent classic laryngeal mask airway (cLMA) placement was an effective alternative means for ventilation to provide temperate oxygenation in this case.